Obtaining information about closures of navigable elements, e.g. roads of a road network, is important in a navigation system. The presence of a road closure has a significant impact upon routing through the road network. A road closure may be likened to a traffic jam associated with an “infinite delay”, such that an alternative routing must be determined to avoid the affected road element(s). Knowledge of the existence of a road closure is of importance to road users even if they are not following a pre-calculated route. For example, if a user is following a familiar route, it is still useful for them to be aware if a road closure is present affecting the route so that they may determine an alternative route, with or without the assistance of a navigation system.
Road closure information may be provided to a user, e.g. together with other traffic information, during navigation along a route via an in-vehicle navigation device, such as a portable device (PND) or integrated device, or may be provided as an input to an Advanced Driver Assistance System (ADAS) device. Road closure information may also be used for route planning, e.g. by a navigation or ADAS device, before commencing a journey, or to recalculate a fastest route during a journey if conditions change during traversal along the route.
A road closure is typically a dynamic event, temporarily affecting a road element or elements, and it is therefore desirable to be able to obtain information relating to road closures in the context of a “live” system, i.e. indicative of the relatively current condition of the road network. The constraints on available processing resources and memory in the context of a “live” system present further challenges in determining road closure information in a “live” system.
Conventional systems for obtaining information about road closures typically rely upon data obtained from third parties. For example, such data may be included in “Traffic Message Channel” (TMC) messages that may be broadcast over an FM network, or other similar third party messages. Such information may be based upon data obtained from sources such as police reports, or road agencies/administrators. However, there are some drawbacks in relying upon third party data relating to road closures, since such data is not always accurate, and may not be up to date.
The Applicant has realised that there remains scope for improvement in methods and systems for obtaining information relating to the closure of a navigable element, e.g. for provision to users and/or navigation or ADAS devices.